How have you configured apache to call your CGI? If you are for example using Apache::Registry as a perl-handler then you might have more luck using the apache request object. Scripts launch by Apache::Registry get passed this as their first (subroutine) arg.

#!/usr/bin/perl

my $request = shift;
$request->send_http_header('text/plain');
$request->print( $request->content() );
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Which I have not tested but should do the trick for you. Read up on the CPAN about Apache modules.

I can't believe it's not psellchecked